*, *::before, *::after { margin:0; padding:0; box-sizing:border-box; }

:root {
  --bg:        #f8f9fb;
  --surface:   #ffffff;
  --text:      #1a1a28;
  --text-dim:  #5c5c6e;
  --text-muted:#9494a4;
  --border:    #e8e9ef;

  --c-qr:      #0ea5e9;
  --c-qr-bg:   #ecf9fe;
  --c-convert: #f59e0b;
  --c-convert-bg:#fffbeb;
  --c-pdf:     #ef4444;
  --c-pdf-bg:  #fef2f2;
  --c-sign:    #8b5cf6;
  --c-sign-bg: #f5f3ff;
  --c-wechat:  #10b981;
  --c-wechat-bg:#ecfdf5;

  --radius: 16px;
  --font: Inter, "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
}

html {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

/* ---- subtle grain overlay ---- */

.bg-grain {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: .25;
  background-image:
    radial-gradient(circle at 20% 50%, rgba(14,165,233,.06) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(139,92,246,.05) 0%, transparent 50%),
    radial-gradient(circle at 50% 80%, rgba(16,185,129,.04) 0%, transparent 50%);
}

/* ---- layout ---- */

body {
  min-height: 100dvh;
  display: flex;
  justify-content: center;
  padding: 0 24px;
}

main {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 960px;
  padding: 96px 0 48px;
}

/* ---- hero ---- */

.hero {
  text-align: center;
  margin-bottom: 64px;
}

.hero-badge {
  display: inline-block;
  font-size: .8rem;
  font-weight: 500;
  color: var(--text-dim);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 5px 18px;
  margin-bottom: 28px;
  letter-spacing: .03em;
}

.hero h1 {
  font-size: 2.6rem;
  font-weight: 800;
  letter-spacing: -.03em;
  line-height: 1.15;
  background: linear-gradient(135deg, #1a1a28 0%, #3d3d56 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 14px;
}

.hero-desc {
  font-size: 1.05rem;
  color: var(--text-dim);
  line-height: 1.5;
}

.hero-line {
  width: 40px;
  height: 3px;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--c-qr), var(--c-sign));
  margin: 24px auto 0;
}

/* ---- tools grid ---- */

.tools {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

/* ---- card ---- */

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 28px 24px 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: inherit;
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 32px rgba(0,0,0,.07), 0 2px 8px rgba(0,0,0,.04);
  border-color: transparent;
}

.card-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.ic-qr      { background: var(--c-qr-bg);      color: var(--c-qr); }
.ic-convert { background: var(--c-convert-bg); color: var(--c-convert); }
.ic-pdf     { background: var(--c-pdf-bg);     color: var(--c-pdf); }
.ic-sign    { background: var(--c-sign-bg);    color: var(--c-sign); }
.ic-wechat  { background: var(--c-wechat-bg);  color: var(--c-wechat); }

.card-body { flex:1; }

.card h2 {
  font-size: 1.05rem;
  font-weight: 650;
  letter-spacing: -.01em;
  margin-bottom: 6px;
}

.card p {
  font-size: .875rem;
  color: var(--text-dim);
  line-height: 1.6;
}

.card-arrow {
  align-self: flex-end;
  font-size: 1.1rem;
  color: var(--text-muted);
  transition: transform .2s ease, color .2s ease;
}

.card:hover .card-arrow {
  transform: translateX(3px);
  color: var(--text);
}

/* ---- footer ---- */

footer {
  margin-top: 72px;
  padding-top: 28px;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: .8rem;
  color: var(--text-muted);
}

footer a {
  color: var(--text-muted);
  text-decoration: none;
}

footer a:hover { color: var(--text-dim); }

/* visually hidden — accessible to crawlers, invisible to users */

.seo-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ---- responsive ---- */

@media (max-width: 768px) {
  .tools { grid-template-columns: repeat(2, 1fr); }

  .hero h1 { font-size: 2.1rem; }
}

@media (max-width: 500px) {
  main { padding-top: 60px; }

  .hero { margin-bottom: 40px; }
  .hero h1 { font-size: 1.8rem; }
  .hero-desc { font-size: .95rem; }

  .tools { grid-template-columns: 1fr; gap: 12px; }

  .card { padding: 22px 20px 20px; gap: 14px; }
  .card-icon { width: 44px; height: 44px; border-radius: 12px; }
}